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Better test program for 128-bit math support

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Clang 3.2 does constant-folding and variable substitution to determine
that the program is equivalent to "return 1".  Splitting the 128-bit
math into a new function seems sufficient to fix this.
This commit is contained in:
Nick Mathewson 2013-04-11 17:52:26 -04:00
parent e9e430403c
commit 85e7de68bc
1 changed files with 23 additions and 17 deletions
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40
configure.ac
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@ -663,32 +663,38 @@ if test x$enable_curve25519 != xno; then
[AC_LANG_PROGRAM([dnl
#include <stdint.h>
typedef unsigned uint128_t __attribute__((mode(TI)));
], [dnl
uint64_t a = ((uint64_t)2000000000) * 1000000000;
uint64_t b = ((uint64_t)1234567890) << 24;
uint128_t c = ((uint128_t)a) * b;
int ok = ((uint64_t)(c>>96)) == 522859 &&
int func(uint64_t a, uint64_t b) {
uint128_t c = ((uint128_t)a) * b;
int ok = ((uint64_t)(c>>96)) == 522859 &&
(((uint64_t)(c>>64))&0xffffffffL) == 3604448702L &&
(((uint64_t)(c>>32))&0xffffffffL) == 2351960064L &&
(((uint64_t)(c))&0xffffffffL) == 0;
return ok;
}
], [dnl
int ok = func( ((uint64_t)2000000000) * 1000000000,
((uint64_t)1234567890) << 24);
return !ok;
])],
[tor_cv_can_use_curve25519_donna_c64=yes],
[tor_cv_can_use_curve25519_donna_c64=no],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([dnl
#include <stdint.h>
typedef unsigned uint128_t __attribute__((mode(TI)));
], [dnl
uint64_t a = ((uint64_t)2000000000) * 1000000000;
uint64_t b = ((uint64_t)1234567890) << 24;
uint128_t c = ((uint128_t)a) * b;
int ok = ((uint64_t)(c>>96)) == 522859 &&
(((uint64_t)(c>>64))&0xffffffffL) == 3604448702L &&
(((uint64_t)(c>>32))&0xffffffffL) == 2351960064L &&
(((uint64_t)(c))&0xffffffffL) == 0;
return !ok;
])],
#include <stdint.h>
typedef unsigned uint128_t __attribute__((mode(TI)));
int func(uint64_t a, uint64_t b) {
uint128_t c = ((uint128_t)a) * b;
int ok = ((uint64_t)(c>>96)) == 522859 &&
(((uint64_t)(c>>64))&0xffffffffL) == 3604448702L &&
(((uint64_t)(c>>32))&0xffffffffL) == 2351960064L &&
(((uint64_t)(c))&0xffffffffL) == 0;
return ok;
}
], [dnl
int ok = func( ((uint64_t)2000000000) * 1000000000,
((uint64_t)1234567890) << 24);
return !ok;
])],
[tor_cv_can_use_curve25519_donna_c64=cross],
[tor_cv_can_use_curve25519_donna_c64=no])])])